Bicycle handlebar assembly



FIG. 1 is a front view of a bicycle handlebar assembly showing my new design;

FIG. 2 is a left end view thereof;

FIG. 3 is a back view thereof;

FIG. 4 is a right end view thereof; and,

FIG. 5 is a top view thereof.

The broken lines shown are for illustrative purposes only and form no part the claimed design. 

The ornamental design for a bicycle handlebar assembly, as shown and described. 